Observatories

Leah

Astrophoto Gallery

CSSC's historic 8" Alvan Clark refractor telescope is the original 1883 instrument donated by founder Anthony Chabot.

In 1883, Anthony Chabot, a successful hydraulic engineer and provider of water to the city of Oakland, agreed to fund an 8-inch telescope. Mr. Chabot subsequently funded the new observatory as well, which opened in downtown Oakland on November 24th of the same year.

The 8" refractor was named "Leah."

Right: Chabot 8-inch Refractor, "Leah," at Mountain Boulevard Site

Rachel

CSSC's historic 20" Warner and Swasey refracting telescope, installed at Chabot Observatory in 1915.

Astrophoto Gallery

Chabot's 20-inch refracting telescope was commissioned in 1914 from Warner & Swasey, with optics by John Brashear.  This telescope was named "Rachel."

Left: Rachel, in its most recent home on Skyline Boulevard. 

In June 1999, Rachel was removed from the site where she had served the public for 75 years.  Extensive dismantling, cleaning, and refurbishment were performed.  Early in 2000, Rachel was installed in her new dome at the new Chabot Space & Science Center.

Right:  Rachel in the early days at Chabot Observatory on Mountain Boulevard.

Nellie

Astrophoto Gallery

Chabot's new 36" reflector, "Nellie," is housed in a rolling roof observatory, allowing access to 180 degrees of sky. This modern, research-quality telescope offers breathtaking views of the cosmos.

NellieCam! NEW:  Near-realtime images taken through Nellie on selected Friday and Saturday nights.  (Note: NellieCam is currently in an evaluation mode and is not operating on a scheduled basis.)

Extreme Make-over, Observatory Edition!
(Click for full-length version: 8 MB)

 

Research

Astronomy Research Programs At Chabot

	Extra-solar Planets Research
	Asteroid Hunter Video Clip Asteroid Search Program
	Student Astronomer Program
	Astrophotography

Astrophotos

Astrophoto Gallery

M 42 January 14, 2008 Picture taken by the Exoplanets Team  through Chabot's 20-inch refractor, Rachel

Chabot Astrophoto Walk of Stars
Leah	Rachel	Nellie

Solar Observing

Explore the DAY Skies at the Chabot Observatories

Solar Viewing

At Chabot in the light of day we bring out Sunspotters, a Coronado Hydrogen-Alpha PST telescope, a Coronado SolarMax 70 H-alpha telescope, and a Coronado Calcium-K filter solar scope.  Each of these scopes gives us a different view of the Sun, allowing our visitors to explore different solar features. 

Views of the Sun through these scopes are available most Saturdays and Sundays, weather permitting.

Sunspotters

The "safe solar viewing" Sunspotter™ telescope reveals any sunspots that may be crossing the Sun's photosphere (visible surface) on a given day.  Sunspots are magnetic disturbances on the Sun, quite often as big as the planet Earth--and can get much larger than that!

Hydrogen Alpha Filter Telescopes

Through these special telescopes, which filter out all of the Sun's light except for a special wavelength of red that emitted by hot hydrogen gas, we are able to view features in the Sun's atmosphere--features such as filaments and prominences:  cooler gases in the Sun's atmosphere that might be thought of as "clouds" on the Sun.  These "clouds," however, are much larger than the Earth and made of hot hydrogen gas. 

Calcium-K Filter Telescope

Another telescope with a special filter allows us to see the Sun only in the blue light emitted by hot calcium, revealing surface hot spots in a similar way to how a Sunspotter reveals the cooler locales of sunspots. /p>

Meridian Transit

Above:  The Chabot Transit Telescope in its housing at Mountain Blvd., Oakland, California. Photo credit: Jim Ferreira

The Earle Linsley Meridian Room at Chabot Space & Science Center, named in honor of Chabot’s second director, houses a 4 1/8-inch Fauth Transit telescope.

In 1885, the transit telescope, along with solar and sidereal clocks, was installed at the original Oakland Observatory, later known as Chabot Observatory. Astronomers made timekeeping observations every Friday night, setting the official time for Oakland. The instruments automatically rang a bell at Oakland City Hall twice a day. The telescope was moved in 1915 to Chabot’s Mountain Boulevard site, where it remained in operation until its relocation in 2000.

Why Use a Telescope to Tell Time?

A hundred years ago, ships used the time and measurements of star positions in the sky to determine their location. But mechanical clocks of the day were not very accurate, and time was of the essence in calculating geographic longitude.

We can observe the Sun and other stars traveling across the sky at a constant rate each day.  By knowing one’s exact position on earth, as well as a star’s position in the sky, astronomers would mark the time when a star passed or “transited" an imaginary line in the sky north to south, the “meridian”. Sea captains regularly reset their navigational clocks using standard time based on these meridian transit observations. Knowing the exact time remains very important to navigation, even today.

The Big Clock in the Sky

The first clock was the sky, the Sun the hour-hand.  What is a clock but a numbered dial with hands that move constantly around it, their positions indicating the time? Though as a “clock” the sky is very accurate, people’s ability to read the exact time by simply looking at the position of the Sun is limited.  You can tell when it is around noon by noting when the Sun reaches its highest point in the sky, when it crosses the meridian.  But how easily can we mark the precise moment when this event occurs?

The answer to this is to use a tool—and it doesn’t take high technology to find the precise moment when the Sun crosses the meridian.  A stick casting a shadow on the ground declares noon when the shadow is shortest.  A hollow tube pointing exactly at the correct point on the meridian announces noon when we see the Sun through it.

The known positions of other stars also can be used to tell time—and though their light is too faint to cast much of a shadow, we can still mark the moment that they cross the meridian by watching the meridian and waiting for the event.  And we can improve our ability to see faint stars and the instant that they transit the meridian by using a telescope instead of a hollow tube. In the scheme of the great sky clock, the meridian transit telescope is the hour-hand pointing at the dial, the stars’ known coordinates the dial’s numbers.

Telescope Makers' Workshop

“Surely the making and putting into use of a powerful astronomical telescope goes far toward properly orienting one’s self in the great scheme of things.”
- Russell Porter

I Can Build A Telescope?

Yes! Open to all ages, the Telescope Makers’ Workshop is an all-volunteer group committed to helping people build their own telescopes. Bring your interest and curiosity, and we’ll provide knowledge, enthusiasm, and advice to help you complete your telescope-making projects. No experience  necessary.

Originally founded in 1930, the Telescope Makers’ Workshop has operated continuously since 1967, guiding hundreds of members in building their own telescopes. People of all ages and backgrounds have successfully completed fun-to-use instruments that provide hours of enjoyable observing of the night sky. Many have gone on to build more complex designs that are available to the amateur telescope maker today.

[ Learn more about what's involved in building a telescope. ]

Where & When

The Telescope Makers’ Workshop is held every Friday night from 7:00 p.m. to 10:00 p.m., excluding major holidays (e.g. Christmas Day and New Year's Day) that fall on Fridays. The Workshop is always closed on Memorial Day Weekend. Attendance every Friday night is not mandatory, and members work at their own pace.

The Workshop meets in its new quarters at the new Chabot Space & Science Center, 10000 Skyline Blvd., Oakland. Contact us for more specific details:

Contact: E-mail -- (510) 406-1914.

What Kind of Telescope Can I Build?

Most of our members build Newtonian telescopes on Dobsonian mounts. These telescopes and mounts are economical, fun to use, and relatively simple to build. Newtonian telescopes are much larger and perform much better than inexpensive department store telescopes, and building one is a terrific learning experience.

How Do I Build A Telescope Mirror?

The process of making a telescope mirror is very simple and requires no previous experience. With mirrors, a concave, spherical-shaped surface will reflect light from a star to a focused point. Two pieces of round glass are used, one of which is the mirror blank, the other the tool. By placing the mirror blank on top of the tool with a slurry of water and grinding compound between them, then pushing the mirror blank across the tool until it overhangs the bottom piece of glass by about one-third its diameter, the center area of the mirror blank is ground away faster than the edge. After about seven strokes, the tool and mirror blank are rotated a quarter turn from each other so another part of the mirror’s surface is ground. Thus a concave surface is ground out of the mirror blank.

Using successively finer grinding compound, and then a polishing compound, a polish is put on the surface of the glass. Fine tuning of this surface, called figuring, puts the glass into the best shape for focusing starlight.

How Long Does It Take & How Much Does It Cost?

We charge no fees to attend the workshop. All of our instructors are unpaid volunteers. You will be expected to buy your own materials, including a mirror blank, a grinding tool, a rinse bucket, a spray bottle and paper towels. The workshop carries a small stock of mirror kits for sale at cost, and we can provide you with the names of other sources.

The typical 8”-diameter telescope mirror blank and tool cost under $150. A completed 8” telescope on a wooden Dobsonian mount can be built for under $300, compared to $400 - $900 for a commercially-made one.

It normally takes around forty hours of work to complete your first mirror. Some of this work is easier to do in the workshop, but much of it can be done at home, an hour or so at a time. Depending on your skills, you might spend a similar amount of time constructing a wooden mounting for your telescope with just a hammer, saw and screwdriver.

Who Builds A Telescope?

Since its start in 1967, the Telescope Makers’ Workshop has seen hundreds of members build their own telescopes. People of all ages and backgrounds have successfully completed fun-to-use instruments that provide hours of enjoyable observing of the night sky. Many have gone on to build more complex designs that are available to the amateur telescope maker today.

Telescopes built at the Telescope Makers’ Workshop have won awards for mechanical, design, and optical excellence at many of the major national telescope makers’ conferences, including the Riverside Telescope Makers Conference, Stellafane, and the Texas Star Party.

Many people build a telescope because it is less expensive than purchasing a commercial instrument. Parents often pair up with their children to do a family project, and school-aged children complete telescopes as a science fair project or homework assignment. Members sometimes come with just their curiosity and a desire to view the heavens with something they have made themselves. Whatever the reason, our members find advice and a sense of camaraderie among the many others who have found enjoyment in making their own telescope.